I would not be surprised either way if Estes completely discontinued stocking 4” nosecones and tubes or if they restocked them.
If there are any in the pipeline, they will probably come back. But I think Estes is mostly about selling motors, and rocket kits are a way to create the market for motors, just like Epson makes money on ink cartridges, and they will almost give to a printer for free so you will buy ink.
If that’s the case, then it might make sense for Estes to drop all 4” parts. There are no Estes BP motors that can fly a 4” rocket, at least not one that uses an MDRM cone or body tube. The 3” rockets like the Estes Doorknob are just about the biggest thing you can fly on a BP motor made by Estes, so I would not be at all surprised if those are the biggest rockets we see from Estes going forward.